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OSPF Questions 2

July 28th, 2019 in ROUTE 300-101 Go to comments

Question 1

Explanation

Loading: In this state, the actual exchange of link state information occurs. Based on the information provided by the DBDs, routers send link-state request packets. The neighbor then provides the requested link-state information in link-state update packets. During the adjacency, if a router receives an outdated or missing LSA, it requests that LSA by sending a link-state request packet. All link-state update packets are acknowledged.

Reference: http://www.cisco.com/c/en/us/support/docs/ip/open-shortest-path-first-ospf/13685-13.html

Question 2

Question 3

Question 4


Question 5

Explanation

+ Standard areas can contain LSAs of type 1, 2, 3, 4, and 5, and may contain an ASBR. The backbone is considered a standard area.
+ Stub areas can contain type 1, 2, and 3 LSAs. A default route is substituted for external routes.
+ Totally stubby areas can only contain type 1 and 2 LSAs, and a single type 3 LSA. The type 3 LSA describes a default route, substituted for all external and inter-area routes.
+ Not-so-stubby areas implement stub or totally stubby functionality yet contain an ASBR. Type 7 LSAs generated by the ASBR are converted to type 5 by ABRs to be flooded to the rest of the OSPF domain.

Reference: http://packetlife.net/blog/2008/jun/24/ospf-area-types/

Question 6

Explanation

NSSA External LSA (Type 7) – Generated by an ASBR inside a Not So Stubby Area (NSSA) to describe routes redistributed into the NSSA. LSA 7 is translated into LSA 5 as it leaves the NSSA. These routes appear as N1 or N2 in the routing table inside the NSSA. Much like LSA 5, N2 is a static cost while N1 is a cumulative cost that includes the cost upto the ASBR.

OSPF_LSAs_Types_7.jpg

Question 7

Explanation

OSPFv3 uses the well-known IPv6 multicast addresses, FF02::5 to communicate with neighbors. The FF02::5 multicast address is known as the AllSPFRouters address. All OSPFv3 routers must join this multicast group and listen to packets for this multicast group. The OSPFv3 Hello packets are sent to this address.

Note: All other routers (non DR and non BDR) establish adjacency with the DR and the BDR and use the IPv6 multicast address FF02::6 (known as AllDRouters address) to send LSA updates to the DR and BDR.

The answer “link-local addresses” is also correct too. The reason is OSPFv3 routers use link-local address (FE80::/10) on its interfaces (as the source address) to send Hello packets to FF02::5 (as the destination address). So in fact this question is not clear and there are two correct answers here.

Note: The two IPv6 multicast addresses FF02::5 and FF02::6 have link-local scope.

Question 8

Explanation

NSSA External LSA (Type 7) – Generated by an ASBR inside a Not So Stubby Area (NSSA) to describe routes redistributed into the NSSA. LSA 7 is translated into LSA 5 as it leaves the NSSA. These routes appear as N1 or N2 in the routing table inside the NSSA. Much like LSA 5, N2 is a static cost while N1 is a cumulative cost that includes the cost upto the ASBR.

OSPF_LSAs_Types_7.jpg

Question 9

Question 10

Comments
  1. Anonymous
    August 5th, 2017

    Hi!

    Can you please confirm the answer to question 1, i think its B (Loading)

    https://www.cisco.com/c/en/us/support/docs/ip/open-shortest-path-first-ospf/13685-13.html

    Loading

    In this state, the actual exchange of link state information occurs. Based on the information provided by the DBDs, routers send link-state request packets. The neighbor then provides the requested link-state information in link-state update packets.

  2. Sq
    August 6th, 2017

    Question 3

    Refer to the exhibit. A network engineer executes the show ipv6 ospf database command and is presented with the output that is shown. Which flooding scope is referenced in the link-state type?
    (Exhibit missing)

    A. link-local
    B. area
    C. AS (OSPF domain)
    D. reserved

    The exibit is showing:

    Link (Type-8) Link states (Area 0)

    As its type 8 shouldn’t it be the link-local flooding scope ?

  3. anu
    August 18th, 2017

    Refer to the exhibit. A network engineer executes the show ipv6 ospf database command and is presented with the output that is shown. Which flooding scope is referenced in the link-state type?
    (Exhibit missing)

    A. link-local
    B. area
    C. AS (OSPF domain)
    D. reserved

    Whats the correct answer?

  4. anu
    August 18th, 2017

    When OSPF is forming an adjacency, in which state, the actual exchange of information in the link?
    A. INIT
    B. loading
    C. exstart
    D. exchange

    Whats the answer?

    Exstart

    Once the DR and BDR are elected, the actual process of exchanging link state information can start between the routers and their DR and BDR.
    In this state, the routers and their DR and BDR establish a master-slave relationship and choose the initial sequence number for adjacency formation. The router with the higher router ID becomes the master and starts the exchange, and as such, is the only router that can increment the sequence number. Note that one would logically conclude that the DR/BDR with the highest router ID will become the master during this process of master-slave relation. Remember that the DR/BDR election might be purely by virtue of a higher priority configured on the router instead of highest router ID. Thus, it is possible that a DR plays the role of slave. And also note that master/slave election is on a per-neighbor basis.

    Loading

    In this state, the actual exchange of link state information occurs. Based on the information provided by the DBDs, routers send link-state request packets. The neighbor then provides the requested link-state information in link-state update packets. During the adjacency, if a router receives an outdated or missing LSA, it requests that LSA by sending a link-state request packet. All link-state update packets are acknowledged.

  5. Pif
    August 19th, 2017

    Hello anu,

    Please , it will be helpful to share the dumps. I don’t find the questions.

    my e mail is loofy666 @ gmail . com

    I download from this site Route_April_2016 but the questions don’t correspond .

    Please help me

  6. Anonymous
    August 21st, 2017

    Passed today 9xx,
    Study the labs from here and check out for the latest dumps on IT-Libraries website there are a lot of users that use it and you can see if the dumps are still valid or not.

    good luck

  7. Who am I to judge
    August 22nd, 2017

    @Anu @Sq

    Question3:

    It must be link local

  8. Anonymous
    August 25th, 2017

    Failed today with 760pts….although I cleared all my labs , loads of new questions ,don’t trust any dumps…study hard chaps….and loads of simlet ( IPV6 , ACL, NAT, NAT-PT ETC ETC )

    IT Libraries hasn’t got all questions ..

    ACL very important ( IPV6 and IPV4 both)

    I was using my old 642-902 books :(, please get the new cert guide for CCNP route 300-101)

  9. Steffy
    August 28th, 2017

    Hello guys, for latest valid dump with continuous update, please contact me at steffyshirls @ gmail .com

  10. Anonymous
    September 3rd, 2017

    When OSPF is forming an adjacency, in which state, the actual exchange of information in the link?
    A. INIT
    B. loading
    C. exstart
    D. exchange
    Whats the answer?
    Exstart
    Once the DR and BDR are elected, the actual process of exchanging link state information can start between the routers and their DR and BDR.
    In this state, the routers and their DR and BDR establish a master-slave relationship and choose the initial sequence number for adjacency formation. The router with the higher router ID becomes the master and starts the exchange, and as such, is the only router that can increment the sequence number. Note that one would logically conclude that the DR/BDR with the highest router ID will become the master during this process of master-slave relation. Remember that the DR/BDR election might be purely by virtue of a higher priority configured on the router instead of highest router ID. Thus, it is possible that a DR plays the role of slave. And also note that master/slave election is on a per-neighbor basis.
    Loading
    In this state, the actual exchange of link state information occurs. Based on the information provided by the DBDs, routers send link-state request packets. The neighbor then provides the requested link-state information in link-state update packets. During the adjacency, if a router receives an outdated or missing LSA, it requests that LSA by sending a link-state request packet. All link-state update packets are acknowledged.
    Pif August 19th, 2017
    Hello anu,

  11. Correction
    September 23rd, 2017

    Question 1

    When OSPF is forming an adjacency, in which state, the actual exchange of information in the link?
    A. INIT
    B. loading
    C. exstart
    D. exchange

    B. Loading is the correct answer.

  12. learner
    October 15th, 2017

    Question 1

    I believe based on information from link below it should be C: EXSTART

    When OSPF is forming an adjacency, in which state, the actual exchange of information in the link?
    A. INIT
    B. loading
    C. exstart
    D. exchange

    https://www.computernetworkingnotes.com/ccna-study-guide/ospf-neighbor-states-explained-with-example.html

  13. jonzo
    October 17th, 2017

    Hi folks,

    Can I get clarification on Q1?

    I am uncertain about how it is worded. Is at asking about routing information or link state information?

    Database sequence numbers and master/ slave logic negotiated = exstart state
    Routing information exchanged = loading state

    The answer would depend on the interpretation of the question?

  14. Corner
    November 22nd, 2017

    Q1. Answer is loading.

    exstart = forming master/slave relationship
    exchange = exchange Database Descriptors (LSA headers only)
    loading = exchange of full LSA (the ones the router doesnt have already)

  15. 1Way
    January 8th, 2018

    Q4 is vague, it says “exchange of information” not exchange of LSA’s. DBD’s are information so for me the answer is D ‘Exchange’.

  16. 1Way
    January 8th, 2018

    Sorry meant Q1 in above post.

  17. Rando
    January 14th, 2018

    Q1 is confusing due to wording.
    Exstart is mistakenly listed due to similar wording being “the actual process of exchanging link state information can start”.
    The Correct answer must be Loading… this is highlighted in the document that is referenced..
    ” Loading – In this state, the actual exchange of link state information occurs.”

    Q2 is :
    Intra-Area (O)
    Inter-Area (O IA)
    External Type 1 (E1)
    NSSA Type 1 (N1)
    External Type 2 (E2)
    NSSA Type 2 (N2)

    This can be proved by having one of each network type using the same IP address on different routers all connecting to one hub and slowly removing each from top to bottom.

  18. somebody
    February 1st, 2018

    For Q1 , from my little understanding I think the answer is (loading)
    Because
    Exstart: is the actual (process) of exchanging link state information can (start) not the exchange it self
    Loading: is the actual exchange of link state information occurs.
    So the exchange it self happens in loading not Exstart.

  19. CCNP_ROUTE
    March 7th, 2018

    For CISCO exam… what is the correct answer for Q1? I fail on test just for one question and this questions show in my test… please.. help me

  20. Marcus
    April 14th, 2018

    Q3, about “flooding scope”. Answer is A (link-local), NOT B.

    “Link LSAs (Type 8)—Have local-link flooding scope and are never flooded beyond the link with which they are associated.”

    https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/iproute_ospf/configuration/15-mt/iro-15-mt-book/ip6-route-ospfv3.html

    “Type 8 LSAs only exist on a local link” (Official Cert Guide).

  21. Elv
    April 16th, 2018

    some old ospf questions from this site https://www.digitaltut.com/ospf-questions-2

  22. CCNP_learner
    April 22nd, 2018

    Can anybody clarify on the answer for Q9?
    A route map was configured and it was distributing OSPF external routes.

    A. Distributing E1 only
    B. Distributing E1 and E2 using prefix list
    C. Distributing E1 and E2 using access list
    D. Distributing E2 routes

  23. Bennis
    April 27th, 2018

    @CCNP_Learner
    I think both B and C are correct, but if you consider that ACLs are used for many things; And Prefix-Lists are JUST used to matching Routes, then you can say that B is more correct,,

  24. ShutNoShut
    July 30th, 2018

    Q1 answer is Exstart the question is “Starts Exchanging INFORMATION in the Link” so electing of Master and Slave is the first exchange of information through comparing each router ID. That’s the first information being shared to each router thus Exstart is the answer.

  25. ShutNoShut
    July 30th, 2018

    For Q3 we need to know that missing exhibit the answer could be Area/Intra-Area if LSA Type 9 or Link-Local if LSA Type 8.

  26. Anonymous
    August 6th, 2018

    Q1 there is a lot of debate. It is all in the wording. The Question asks:
    “in which state, the actual exchange of information in the link”
    note “Actual Exchange”

    Cisco state in their OSPF Neighbor States Dohttps://www.cisco.com/c/en/us/support/docs/ip/open-shortest-path-first-ospf/13685-13.html

    Loading
    In this state, the actual exchange of link state information occurs

    Therefore the answer should be B

    ExStart is just setting up for the exchange
    Loading is just loading the DBD’s not the full info

  27. Anonymous
    August 30th, 2018

    I cant see the questions.
    i see answers only. is that for all?

  28. Anonymous
    September 18th, 2018

    Since Cisco IOS release 15.1(2)S, Cisco uses the path selection order from RFC 3101 which obsoletes RFC 1587. What this means is that it prefers N1 routes before E1 and N2 over E2 routes. In other words, the prefered path list is O > O IA > N1 > E1 > N2 > E2.

  29. 6U
    September 29th, 2018

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    W w

    w.cc iedumps.xyz/ccie_rs.php?ut m_source=bbs&utm_medium=bbs

  30. Camp
    October 25th, 2018

    Q2:

    Answer is: B A C E D F

    This is a good site to understand it…
    https://networklessons.com/ospf/ospf-path-selection-explained/

  31. Camp
    October 25th, 2018

    Q2 again… sorry, bad order… here is the good:

    B Intra-Area (O)
    A Inter-Area (O IA)
    E External Type 1 (E1)
    C NSSA Type 1 (N1)
    D External Type 2 (E2)
    F NSSA Type 2 (N2)

  32. Camp
    October 25th, 2018

    Hate this… I cant edit and now I have 2 bad order above this…

    Q2:

    OSPF chooses routes in which order, regardless of route’s adminstrative distance and metric?
    A. Interarea
    B. Intra-area
    C. NSSA type1
    D. NSSA type 2
    E. External type1
    F. External type2

    B A E C F D !!!

  33. RouteRider
    November 24th, 2018

    @kaktus
    RFC2328 says:”Compare the AS external path described by the LSA with the existing paths in N’s routing table entry, as follows. If the new path is preferred, it replaces the present paths in
    N’s routing table entry. If the new path is of equal preference, it is added to N’s routing table entry’s list of paths.
    (a) Intra-area and inter-area paths are always preferred over AS external paths.
    (b) Type 1 external paths are always preferred over type 2 external paths. When all paths are type 2 external paths, the paths with the smallest advertised type 2 metric are always preferred.”

    Intra-Inter-Ext 1-NSSA 1-Ext 2-NSSA2

  34. Dany1
    November 27th, 2018

    I agree with RouterRider for formula 0 > O IA > E1 > N1 > E2 > N2. This is according with IOS 15. What is written in ine blog page was a rule applied to IOS 12.x

  35. José
    December 26th, 2018

    Q1, Answer B:
    In this state, the actual exchange of link state information occurs.

  36. WarpRider
    January 3rd, 2019

    Q1 agree with Jose

    First sentence is the explanation on the link provided below the question says exactly that:

    Loading
    In this state, the actual exchange of link state information occurs.

  37. Alex
    January 9th, 2019

    Correct Answer: ABECFD.
    https://forum.networklessons.com/t/ospf-path-selection-explained/969/29

    OSPF doesn’t make a difference between inter-area or intra-area external routes. It doesn’t matter where the external route originated, it’s the cost that makes the difference.

    When I booted up this lab again, I did find something interesting. When I wrote this lesson, I used IOS 12.4 and this is the list that OSPF uses for path selection:

    Intra-Area (O)
    Inter-Area (O IA)
    External Type 1 (E1)
    NSSA Type 1 (N1)
    External Type 2 (E2)
    NSSA Type 2 (N2)
    Since Cisco IOS release 15.1(2)S, Cisco uses the path selection order from RFC 3101 which obsoletes RFC 1587. What this means is that it prefers N1 routes before E1 and N2 over E2 routes. In other words, the preferred path now is:

    Intra-Area (O)
    Inter-Area (O IA)
    NSSA Type 1 (N1)
    External Type 1 (E1)
    NSSA Type 2 (N2)
    External Type 2 (E2)
    So if you have an N1 route and an E1 route, it doesn’t matter where those originated…OSPF will prefer the N1 route (if you run at least IOS 5.1(2)S :grin:

    Hope this helps!

    Rene

  38. ANANSWERABOUTMISMATCHEDQUESTION
    April 27th, 2019

    Hello guys, Digitaltut , just wanted to point here some mismatch between two of the questions here and the Composite questions. Here under OSPF 3 questions, we have the following question:
    When OSPF is forming an adjacency, in which state, the actual exchange of information in the link? —> Loading

    On the composite questions absolutely the same question has an answer “Exstart”.

    * Basically as per my understanding the Exstart is the moment when two neighbors negotiate the DR/BDR states and master-slave info.
    * During the Loading state the two neighbors are already exchanging information provided by the DBD’s and just exchange some LSR and LSU messages based on the information in the DBD and depending if it’s outdated from their perspective.

    So, according to that it seems that during Exstart the adjacency is formed, and during the Loading the adjacency is already formed and the DBD info is exchanged. So, I suppose the Exchange should be the correct answer in both.

  39. Greeners
    April 27th, 2019

    @ANANSWERABOUTMISMATCHEDQUESTION
    @Everyone

    In summary, my penny’s worth –

    INIT – Hello Packet sent, nothing yet received from neighbor. Not yet 2 Way.
    2Way – Hello packet received back from neighbor. Sending router can see it’s own router ID.
    Exstart – Master / Slave Election
    Exchange – Exchange of DBD’s between routers (A summary of which routes each of the routers have in their databases.
    Loading – ‘Actual’ Exchange of routes not known between both routers so that their DB’s match.
    Full – Databases ‘Full’ on both routers.

  40. Dave
    May 20th, 2019

    @Everyone

    Which OSPF patch selection should be used for the exam?
    Depending on the IOS version it has 2 correct answers.

  41. Rey
    June 25th, 2019

    Q7 Answer should be B. Link Local Addresses

    Here is from the “new-route-questions-part-5”

    Question 44

    What type of address OSPFv3 uses to form adjacency and send updates?

    A. FF02::5
    B. link-local
    C. IPv4 address
    D. IPv6 address multicast

    Answer: B

  42. Edwars
    August 27th, 2019

    can someone please share the dumps of 2019?
    my e mail is the_edwinhank @ hotmail com

  43. aurisa
    October 13th, 2019

    As CCNP_learner, I do not see the whole scenary to choose in Q9 option B. Does anybody know why it is the chosen option? A route map could differentiate E1 and E2 based on different criteria, possibly access list and prefix list, couldn’t it?

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